1. Field of the Invention
The present invention relates to a method for remotely controlling a sol-gel transition of hydrogels and a method for delivering a drug using the same. More specifically, the invention relates to a method of remotely controlling a sol-gel transition of polyethylene glycol (PEG)-containing hydrogels—three-dimensional networks of crosslinked polymer chains—by X-ray irradiation, and relates to a method for delivering a drug using the same.
2. Background of the Related Art
Phase transition triggered by external perturbation is quite important for “intelligent materials” and a key issue in diverse fields ranging from biomedicine to chemistry, physics, and materials science.
Hydrogels—three-dimensional networks of crosslinked polymer chains—exhibit transitions in response to perturbations such as electric fields, temperature changes, pH changes, concentration changes, enzymes, electron beams, sound, and light. Hydrogels are actively studied with the objective to develop new technologies to control fluidity, viscoelasticity, solvent volatility, optical transmission, ion transport, and other properties.
Light irradiation is an interesting candidate as a “remote stimulus”. However, versatile remote control by ultraviolet and visible light remains a challenge, in particular for thick opaque objects because of low penetration.